C I think because the lines intercept at a common point
-7x+y=42
y=42+7x
5x+13y=66
Substitute for y (meaning put 42+7x into the equation above instead of y because they are equal - see second line of my answer above)
5x+13[42+7x] = 66
5x +546 = 66
5x=66-546
5x=-480
x=-480/5
x=-96
Answer: both of them made ok estimates but i think issacs was better. hope this helps! ^-^
Step-by-step explanation: